Wall-Flow Type System to Replace Existing Wet Element Filter Systems used in Typical LHD in Underground Operations

ACARP project C25073 was proposed by industry stakeholders seeking a potential solution that both improves worker health through improved underground air quality and reduces operational costs associated with currently implemented technology used to control diesel particulate emissions in that environment.

The need to protect workers from diesel particulate matter (DPM) had lead the underground coal mining industry to install disposable filter systems on their vehicles. While the disposable filters are efficient at removing significant DPM, the following major issues have arisen:

· High cost of operations. Disposable filters cost $250-300/each and need to be changed at least once per shift resulting in an estimated cost of up to $164M/year1, in filters alone, to the NSW underground coal mining industry.

· Improper installation, damaged seals and lack of installing a new filter when the old filter is removed means that workers are still being exposed to excessive amounts of DPM.

The project scope was to develop and demonstrate the potential of a proof-of-concept (PoC) wall-flow DPF2 system suitable for implementation to a Load Haul Dump (LHD) vehicle typical of that used by the Australian underground coal industry. The project was completed successfully with only relatively minor issues relating to control of modal NO2 formation requiring further investigation.

Switching to a wall-flow DPF addresses the cost issue as the on-going costs of these systems are minimal compared to disposable filter systems. It also addresses the health issues as the filters do not need regular replacement in-service reducing the chance of improper installation and seal damage. Since a wall-flow system uses a fixed element particulate filter, the machine operator cannot remove the filter and operate the engine without any filter being installed.

It has been estimated that the implementation of a wall-flow DPF system on diesel engines in the underground coal industry would save the industry up to 80%, inclusive of service costs, over a 3 year period. While wall-flow DPFs will need occasional maintenance, the frequency and time required will be small compared to that of the current disposable filter and it should be possible to do this during scheduled downtime.

ACARP project C25073 was scoped to fund only the proof-of-concept phase of the wall-flow DPF development program. Industrialisation of the project system was beyond the scope of the project budget and is deferred to the next stage.

The proof-of-concept project consisted of five parts as outlined below:

· Onsite Duty Cycle Analysis;

· Engine Setup/Baseline/Correlation to Real World;

· Hot Diesel Oxidation Catalyst (DOC) + Diesel Particulate Filter (DPF) System;

· P13 Design Engineering; Cold Exo-surface DOC + DPF System;

· P1 Cold Exo-surface DOC + DPF System - PoC/Development.

In delivering its objectives, the Orbital team was well supported by the Australian coal industry through the assignment of project monitors and facilitation of onsite data acquisition activities that were sponsored by Centennial Coal at its Newstan operations in NSW. PPK Group made available a test engine and support at no cost to the project.

This ACARP project has successfully demonstrated both DPM emissions reduction and the system robustness potential of a proof-of-concept (PoC) wall-flow DPF system for implementation on a Load Haul Dump (LHD) vehicle typical of that used by the Australian underground coal industry. The project was completed successfully with only a couple issues requiring further investigation. The system looks to have potential as both an OEM and retrofitable solution.

Not only does the implementation of wall-flow DPF technology protect workers from diesel particulate matter (DPM), but it is expected to also offer underground coal mine fleet operators significant reductions in the operating and associated cost of the conventional disposable filter systems which have been relied upon to date. In combination with the adoption of electronic systems to monitor DPF performance, the industrialised solution represents a game-changing opportunity for this sector.